1. Field of the Invention
The invention relates to DC-DC converters and error amplifiers thereof.
2. Description of the Related Art
Portable electronic devices, such as mobile phones, personal digital assistants, and portable multimedia entertainment players, are powered by batteries. A DC-DC converter is required to convert the battery voltage to the required voltage level.
The DC-DC converter comprises an error amplifier, which requires a large compensation capacitor. The compensation capacitor, however, limits the response time of the error amplifier and the stabilization time of the DC-DC converter. The compensation capacitor is too large to be integrated in a chip, and thus connecting wires between the external compensation capacitor and the chips resultingly act as parasitic capacitors and resistors.
In another conventional DC-DC converter, the compensation capacitor is charged or discharged by a large current provided by the error amplifier to speed response of the error amplifier. However, the large charge/discharge current results in more power consumption.
An error amplifier with fast response and low power consumption is thus called for.